An organic electroluminescence (EL) device generally comprises an anode, a cathode, and one or more organic thin film layers sandwiched between the anode and the cathode. When a voltage is applied between the electrodes, electrons are injected from the cathode and holes are injected from the anode into a light emitting region. The injected electrons recombine with the injected holes in the light emitting region to form excited states. When the excited states return to the ground state, the energy is released as light.
Many researches have been made on the applications of organic EL device to display, etc. because of its possibility of a wide selection of emission colors by using various emitting materials in a light emitting layer. Particularly, the research on the materials which emit three primary red, green, blue colors has been made most actively, and the intensive research has been made to improve their properties.
Patent Documents 1 to 4 disclose the compounds wherein 2 or 3 indene structures or indole structures are fused to one benzene ring as the material for organic EL device. In Patent Documents 1 and 2, the indole skeletons are fused to one benzene ring in the opposite directions. In Patent Documents 3 and 4, the indene or indole skeletons are fused to one benzene ring in the same direction.
However, it has been still required in the field of organic EL device to develop new materials which can further improve the device performance.